Logan Connelly’s Engineering Portfolio


 


Contents

Design Projects. 1

Illini Electric Motorsports (FSAE; August 2023 – August 2025) 1

Rear Wing Cross-Brace. 1

Conceptual Gearbox. 1

Monocoque ‘Upside-Down’ Layup Jig. 1

HV Battery Component Mounts. 1

49ers Racing IC (FSAE; August 2025 – Present) 1

Monocoque Preliminary Design. 1

Carbon Fiber Panel Sizing Solver (optiLayup) 1

Obscure Shape Carbon Fiber Component Layup Optimizer (optiLayupOS) 1

Gearbox Ratio Optimization/Acceleration Simulation. 1

Hunter Engineering Company (May 2024 – December 2024) 1

Rough Functional Prototype for a Planned Shop Tool*. 1

Trailer Hitch Mounts for Rolling Chassis. 1

Gimbal Test Stand. 1

Gear Rack Strength Testing Stand. 1

Personal Projects. 1

Personal Projects. 1

Trailer Model 1

2008 Subaru Legacy. 1

2008 Subaru Legacy spec.B. 1

 

 


 

Design Projects

Design Projects are projects wherein I designed and, most often, manufactured the resulting component/assembly.

Illini Electric Motorsports (FSAE; August 2023 – August 2025)

Rear Wing Cross-Brace

A brace intended to be placed between the two rear wing supports (struts) to improve lateral stiffness as well as minimize vibrations from the ride frequency of the car.

Analysis:

-          Performed Modal Analysis to ensure that the cross-brace would minimize vibrations in the rear wing as much as possible

o   Used ride frequency from Vehicle Dynamics team to then target three times said frequency (as per general dampening “rule of thumb”) to practically eliminate primary vibrations of the rear wing.

-          Used basic parallel axis theorem principles to calculate effective bending stiffness of the rear wing struts to then ensure that the cross-brace adds sufficient lateral stiffness such that the rear wing does not deflect in a cornering scenario.

-          Used basic carbon fiber tube bonding qualities to maximize bond strength such that the cross-brace did not fail in tensile loading conditions

Design:

-          Modeled and assembled tube and inserts in Creo and ensured compatibility with chosen clevis and rod end (Fig1.1)

-          Included turnbuckle-like threaded attachments for adjustment of brace length to account for tolerance stackups in both the rear wing struts and the cross-brace itself

-          Provided properly dimensioned and toleranced engineering drawing to machinist such that the tube inserts could be milled and lathed accurately

Retrospective:

-          The biggest point of failure in this design was the choice to only use one effective brace rather than an “X” design. This resulted in additional unexpected loads being transferred through the rear wing main element and the rear wing struts. To avoid this in future designs, the design/stiffnesses of the other members in an assembly must be accounted for especially when using an asymmetrical design.


 

Documentation:

A long metal rod with metal ends

AI-generated content may be incorrect.

Fig1.1; Creo Parametric model of the rear wing cross-brace

Blue drawings of bolts and nuts

AI-generated content may be incorrect.

Fig1.2; Engineering drawing for tube inserts


 

Conceptual Gearbox

Conceptual gearbox with the purpose of evaluating possible switch to single stage planetary gearbox as well as to ring-gear output from planetary output.

Design:

-          Targeted 12:1 reduction ratio as instructed by Vehicle Dynamics Subteam.

-          Used KISSsoft to design conceptual gearbox seen below for trade study

o   This design direction was not chosen and thus these were not implemented

Retrospective:

-          The incredibly small module of the gears at just .550mm; this would have made these gears relatively weak and would have made them extremely expensive to manufacture. In future designs, this is an oversight that will not occur.

-          These gears are also difficult to package with a ring gear outer diameter of 6.11in. Taking into account upright, hub, carrier, and brake rotor and caliper packaging, that diameter would have been much too difficult to accommodate resulting in the decision not to move forward with a single stage gearbox

Documentation:

A grey gear wheel with a blue center

AI-generated content may be incorrect.

Fig 2.1; KISSsoft step model imported to Creo


 

Monocoque ‘Upside-Down’ Layup Jig

A jig to invert the monocoque mold to make the manufacturing process easier; this was also my first foray into design/CAD/engineering.

Design:

-          Used the rough height, length, and width parameters given by Chassis Subteam Lead to create model in Creo; designed with the intention of using 80/20 profile extruded aluminum

-          Created individual 45°, 90°, 180° and 60° brackets to retain the 80/20 aluminum in the desired position

Retrospective:

-          The biggest oversight in this design was the lack of knowledge. Being a freshman in college and not having any STEM programs in high school, I did not know what deflection, stress, and simply supported beams were so, looking back, the only analysis and proof that it could support the structure was that it was intentionally overdesigned because I knew I did not know everything. Having learned stress and deflection principles, under full load the jig would have deflected approximately .028in and would have had a maximum stress of 5100psi, ~5 times less than the 25000psi yield strength.

Documentation:

Fig3.1; Jig in use while manufacturing the monocoque

Fig3.2; Creo Parametric Model (without brackets)


 

HV Battery Component Mounts

Mounts for several components (AIRS, isometer, safety board, HV Active Light, and HV fuse) in the High Voltage Battery.

Design:

-          Designed 3D-printable mounts given the dimensions of the various components

o   Ensured that all mounts could be bonded/positively retained within the HV battery case

Documentation:

A computer generated image of a circuit board

AI-generated content may be incorrect.

Fig4.1; HV Light, Fuse, and Isometer/Safety Board mounts*

*I do not have access to the CAD of these mounts anymore and this is the only screenshot I have


 

49ers Racing IC (FSAE; August 2025 – Present)

Monocoque Preliminary Design

Currently performing preliminary design of a half-monocoque to prove feasibility of switch to half-monocoque chassis for 2027 season

Analysis:

-          Used MATLAB carbon fiber panel sizing solver (discussed on Page 10-11) to size Side Impact Structure (SIS) and floor panels to approximate thickness of chassis panels in order to ensure geometric rules compliance

-          Strictly analyzed Formula SAE 2026 Rules to ensure full rules compliance particularly in bulkhead placement, cockpit opening sizing, and cockpit passthrough sizing.

-          Minimized weight by minimizing size in accordance with rules (particularly in making the SIS exactly 290mm as according to rule F.7.5.1.)

-          Utilized design for carbon fiber manufacturing particularly in minimizing radii as round features are difficult to achieve with aluminum honeycomb core without having anticlastic curvature

-          Utilized design for carbon fiber manufacturing in including 2° draft angles along planned mold parting line (seen in Fig5.1)

-          Length determined via using driver template (seen in Fig5.1) and by including 5-inch clearance for pedal assembly

Design:

-          From approximate carbon fiber sandwich panel sizing, designed a rough monocoque geometry for proof-of-concept to support switch to half-monocoque chassis in 2027

-          Used sketched cockpit and driver templates in SolidWorks to ensure geometric rules compliance

Planned Next Steps:

-          This project was unfortunately deemed not worth it while there are other areas of the car to optimize and because of the exorbitant cost of materials

 

 

 

 

 

 

Documentation:

A grey machine with a metal frame

AI-generated content may be incorrect.

Fig5.1; SolidWorks monocoque assembly with 2025 rear-subframe


 

Carbon Fiber Panel Sizing Solver (optiLayup)

Code to optimize carbon fiber plate/sandwich panel in accordance with user’s desired properties

Code Structure:

-          Initialize analysis by computing every possible combination of ply orientations (0, -45, 45, 90 in accordance with general carbon fiber manufacturing practices) and cores depending on desired number of plies (either per facesheet or whole plate) as input by user

-          Gradually eliminate possible layups by determining overall DFM, presence of bend-bend coupling (typically results from an asymmetrical layup but can also be minimal in asymmetrical layups, so analysis via presence of B-Matrix, the part of the ABCD matrix that defines bend-bend coupling properties), wrapping of unidirectional plies in weave plies, absence of unidirectional plies directly next to core, desired safety factor, desired maximum deflection in loading case

-          Return lightest layup, layup with the highest safety factor, layup with the least stress, layup with the least deflection, and the layup with the best combination of those four factors that can all achieve the user’s desired properties

-          Added implementation of bending about all axes as well as point and distributed loads. Also made it such that the type of beam and load can be text inputs rather than numerical representations.

Optimization for Run-Time Minimization:

-          Check for properties not requiring ABCD matrix calculation that disprove a layups feasibility first as ABCD matrix calculation was initially one of the most computationally intensive processes

-          Split ABCD matrix calculation and abcd matrix calculation as MATLAB’s matrix inversion calculation (at least for a 6x6 matrix) is extremely computationally intensive. Checks for bend-bend coupling and rough quasi-isotropic qualities occur prior to abcd calculation as abcd matrix is only needed for stress/deflection calculations.

-          ABCD matrix calculator, a separate function, also optimized for runtime as much as possible.

-          RESULT: improved run time from 366,000 layups per second to ~6,000,000 layups per second.

Self-Improvements:

-          This was about my 8th function in MATLAB, previously writing the functions used within this function, but the first that was this complex. Additionally, Artificial Intelligence was used very minimally as it was incapable of troubleshooting the code successfully, resulting in 600 hand-coded and -troubleshot lines.

Documentation:

A screen shot of a computer program

AI-generated content may be incorrect.

Fig6.1; optiLayup Pt1

A screen shot of a computer program

AI-generated content may be incorrect.

Fig6.2; optiLayup Pt2

A screen shot of a computer program

AI-generated content may be incorrect.

Fig6.3; optiLayup Pt3

A screenshot of a computer

AI-generated content may be incorrect.

Fig6.4; optiLayup Pt4


 

Obscure Shape Carbon Fiber Component Layup Optimizer (optiLayupOS)

Code to optimize carbon fiber components with enclosed obscure shapes using estimated moment of inertia; primarily for the purpose of the Aerodynamics Subteam to estimate airfoil layups then validate using AnsysACP

Code Structure:

-          Initialize analysis by computing every possible combination of ply orientations (0, -45, 45, 90 in accordance with general carbon fiber manufacturing practices) and cores depending on desired number of plies as input by user

-          Gradually eliminate possible layups by determining overall DFM, wrapping of unidirectional plies in weave plies, absence of unidirectional plies directly next to core, desired safety factor, desired maximum deflection in loading case; an important note here is that the check for bend-bend coupling was eliminated as an enclosed component will always have a ‘symmetrical’ layup as the skin makes a loop

-          Uses estimated MoI and layup’s elastic modulus (1/(A*11 * laminate thickness)) to approximate bending stiffness to then get the lightest, least stressed, highest safety factor, least deflecting, and best overall layups that meet the user’s specifications as with the original optiLayup

Self-Improvements:

-          This was originally a very hastily made function using a constant moment of inertia until I remembered that the main mode of carbon fiber resisting deflection is the parallel axis theorem, a.k.a. a varying MoI based on thickness of the laminate. This extreme oversight and then fixing it reminded me that, while progress is important, progress is also only important if the work being done is useable/accurate.

 

 

 

 

 

 

 

 

 

Documentation:

A screen shot of a computer code

AI-generated content may be incorrect.

Fig7.1: optiLayupOS Pt1

A screen shot of a computer program

AI-generated content may be incorrect.

Fig7.2; optiLayupOS Pt2


 

Gearbox Ratio Optimization/Acceleration Simulation

Performing analysis of gear ratios using previously coded acceleration simulation

Code Structure:

-          From user-input ranges for each gear, perform acceleration simulation for every gearbox in .01 ratio increments for every given range

-          Return time and gearbox of fastest simulated acceleration event

General Concepts Utilized:

-          Included shift times, rough tire model, longitudinal load transfer, aerodynamic downforce and drag, engine torque curve, anti-squat geometry (though no such geometry was present on the car that the model is based on), maximum longitudinal tire force, final drive, gearshifts, launch control, and indications for power-limited points Vs. traction-limited points

Planned Next Steps:

-          This project is on the backburner currently in favor of composites projects.

Documentation:

A screen shot of a computer program

AI-generated content may be incorrect.

Fig8.1; Gearbox optimization code


 

Hunter Engineering Company (May 2024 – December 2024)

Smaller/non-design projects (testing, assembly, general tasks) not shown

Rough Functional Prototype for a Planned Shop Tool*

*This project is under an NDA; information allowed to be provided is extremely limited

Design:

-          Independently designed fully functional product prototype from initial rough sketch from superior

-          Implemented several key design changes which significantly improved functionality/weight

Result:

-          Prototype was demonstrated with full functionality to Vice President of both the company and the engineering department


 

Trailer Hitch Mounts for Rolling Chassis

Trailer hitch mount was requested by senior engineer to facilitate maneuvering of 2-ton rolling chassis via forklift

Analysis:

-          Determined load from A-frame hitch on intended crossbeam to size bolts and supporting plates.

-          Determined necessary clearance for front pin mounts to allow A-frame to tilt backwards as per design criteria

Design:

-          Used existing rolling chassis model to model mounts for A-frame trailer hitch in Creo

-          Used model to produce engineering drawings to provide to both waterjet operator and welder

-          Used stress analysis to apply safety factor of 2 to entire design

Result:

-          Installed finished components on rolling chassis

-          Able to be lifted and bounced by forklift without failure

-          Reduced necessary manpower from 5 people to manually move chassis to only 1 with a forklift

Documentation:

Fig9.1; mounts for A-frame trailer hitch installed on rolling chassis


Gimbal Test Stand

A gimbal test stand to facilitate the process of debugging for software engineers; again, details able to be shared are very limited due to NDA

Design:

-          Used existing gimbal geometry to successfully design improved latching mechanism from prior design

-          Implemented latch from McMaster-Carr into design for ease of assembly/manufacturing

-          Produced engineering drawings to manufacture several components myself and to have the base and the assembly water-jetted and welded, respectively

Result:

-          Stands successfully held gimbals firmly in place

Retrospective:

-          Latch design could have been improved, 3D-printed component of latch broke upon rigorous testing; printed in with better layer-line orientation to resolve issue (initially wanted better print quality of different features, hence ‘wrong’ orientation)

Documentation:

 

 

 

 

 

 

Fig10.1; Gimbal Mounts


 

Gear Rack Strength Testing Stand

A stand to test the ultimate strength of a plastic rack and pinion for an upcoming project*

*This project is under an NDA and thus information able to be shared is limited

Design

-          Used existing aligner components to create a base for the gears

-          Designed bracing and a stand to clamp to a welding table to then add weights to the components and test the strength

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Personal Projects

General mechanical Assembly/Repair experience from automotive work

*Mechanical experience from FSAE is omitted

Personal Projects

Trailer Model

Fig12.1; Trailer Model

-          Modeled 49ers Racing gooseneck trailer as quick favor for a friend in Graphic Design.

2008 Subaru Legacy

Repairs:

-          Replaced wheel bearings

-          Replaced valve cover gaskets

-          Replaced driver-side steering knuckle

-          Replaced front lower ball joints

-          Replaced front sway bar end-links

-          Restored all front brake pins

-          Replaced exhaust manifold

-          Replaced rear door lock actuator

-          Replaced EGR valve

-          Cleaned fuel injectors and replaced seals

-          Diagnosed and repaired clogged midpipe catalytic converter

Maintenance:

-          Multiple oil changes

-          Replaced spark plugs

-          Replaced ignition coils

-          Replaced air filter

-          Brake pad replacement

2008 Subaru Legacy spec.B

Repairs:

-          Diagnosed and replaced faulty O2 sensor

-          Replaced seized rear brake caliper and performed brake system bleed

-          Replaced damaged charge pipe

o   Performed thorough inspection of intake system for metal fragments

Maintenance:

-          Multiple oil changes

-          Cleaned throttle body

-          Tightened boost couplers after one failed under boost